One of the many problems in microwave transmission is the coupling of signals, particularly of different frequencies, into a common output. There are several types of hybrid circuits or couplers for this purpose, but, particularly in coaxial systems, these are usually confined to combiners that are limited to dual inputs, and will produce at least 3db loss at differing frequencies. Additional pairs of units may be combined, and recombined, to accommodate additional frequencies, but at an additional loss of 3db with each combination, and an ultimate limit to the efficiency and the number of frequencies that can, practically, be combined. Furthermore, these hybrid circuits cause intermodulation of the frequencies and tend to degrade the quality of the signals.
It is therefore an object of this invetion to provide a coaxial device for filtering and combining a plurality of different signals into a common coaxial output with negligible intermodulation and a loss of only 1db.